1. Field of the Invention
The present invention relates to a composite machine tool for metal working. More particularly, the present invention relates to a composite machine tool including a vertical lathe and a machining-center type machine tool, e.g., a milling machine.
2. Description of the Prior Art
Typical composite machine tools of the prior art are usually equipped with a single turret tool post with various cutting tools. Machining of each of the cutting tools for one workpiece is operated independently of each other. With such composite machine tools, if the workpiece is heavy, consecutive lathing and milling for many workpieces is difficult and, therefore, a high efficiency of machining operation is not achieved.
Instead of the above, two or more such machine tools may be installed and utilized in combination; however, the workpieces are usually comparatively heavy. Therefore, the workpieces cannot be easily conveyed from, for example, a vertical lathe to a milling machine. Such conveyance requires considerable time. Also, the use of separate maching tools means a large size of the overall machining system and a correspondingly large floor space.